Questions on building a wooden gazebo

[Randomness]

I have some pressure treated 4" wooden poles, which I plan to make a hexagonal wooden gazebo with, by hiring an auger, drilling 6 holes, placing to posts, filling with quick setting concrete and bolting 4x2 between the posts. I then plan to put decking on the 4x2 and a thatch or some sort of roof on rafters on top of the poles.

I've done lots of decking before, but have never used quick setting concrete. I'm wondering:

1. How big I need to make the holes in order to sink the poles in and leave enough room for the concrete?

2. Any other advice on the quick setting concrete - should I make my own or order it in, what stuff to get, what sort of consistency will it / should it have? How best to pour it in etc etc

3. Should the bolts through the poles hold the weight of the decking and everyone in the gazebo etc, or is there a better way to do it - I did consider making a concrete base but the ground is fairly uneven - if I filled a frame with rubble etc, would the concrete fill it and make a base without leaking through the gaps under the frame?

Thanks in advance!

 

[imamartian]

Hi randomness, i'm a DIYer, but have done a fair bit of decking.

I normally use concrete spurs and bolt my joists and posts to these.
For your gazebo, i'd expect pressure treated posts should be ok, and if you want to save time you could use a special post-crete dry mix like this http://mtxit.com/remix3/PMC.htm (other brands are available).

Although i personally wouldn't recommend anything apart from conventional post setting techniques.

As for fixing your joists, i'd use bolts, but also half-lap joints
http://www.woodmagazine.com/woodworking-tips/techniques/joinery/half-lap-joints/?page=6

 

[Randomness]

Thanks imamartian. That postmix looks fantastic, what a genius idea! I might look into the idea of concrete spurs though as you suggest, is that basically a concrete or metal bit that you insert into the concrete first?

 

[imamartian]

I set the concrete spurs into the ground at the corners (or wherever you need a support in your design), and then bolt my joists to them.